@GrouchyOldMan
I think it’s everything you mentioned in concert.
• As long as your plant is healthy the earlier the topping the better. This not only gets any slow down in growth over with very early but also gives the plant more time to establish plant structure and increase in size before flowering starts in full.
• From what I have seen, even though flowering time is generally the same as with photo plants; flowering starts around week 4 and is in full swing by week 5 of the plants life for autos. This equates to 3 - 4 weeks less time in veg mode, plant structure layout and training - due to this growing an auto out as a quad will help to alleviate lack of growth due to shortened ‘veg’ mode. Growing the plant out as a quad will also give you more flowering growth tips in the same amount of time.